CA Foundation · Quantitative Aptitude · Theoretical Distributions
A salesperson in Jaipur closes a sale with probability 0.2 on each independent call. In 5 calls, what is the probability of at least one sale? (Use 0.8^5 = 0.32768)
The probability is 0.67232. The chance of no sale in five calls is 0.8 to the power 5, which is 0.32768. Subtracting this from 1 gives the probability of at least one sale, 0.67232.
- A0.32768
- B0.2
- C0.67232Correct
- D0.99968
Explanation
P(at least one) = 1 − P(none) = 1 − 0.8^5 = 1 − 0.32768 = 0.67232. The value 0.32768 is the probability of no sale, which is the complement. The value 0.99968 is 1 − 0.2^5, which wrongly swaps p and q.
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